Process of making stable calcium perborate.



BEiNHbLD animals, or GHAELOTTENBURG, GERMANK L ASSIGN OR; 'ro .onnmrsonn sooner.

WERKE VORM. DR. HEINRICH BYK, OF:,C.T:ARLOTTENBURG,.GEEMANY A CORPOQA ,rron orenmaany.

raoonss or MAKInGsTABLn'caLorUM EB RBORAT 7 No Drawing.

v To all whom itmay concern:

Be'it known that I, REINHOLD Giiiirsn,

a subject oit' th'e German Emperor, and residentof Charlottenburg, in the Empire of.

Germany, have invented certain new. and useful Improvements in Processes of Making Stable Calcium Perborates, of which the following is'a specification.

According to the Bem'chte clerpeutschen (iiz emz'schen Gesellsckaft,3l,954, a calcium :perborate is formed when sodium perborate 1S .decomposedby calcium chlorid. This calciuin perborate was, however, so unstable that it could not beanalyzed. Further, in the specification of German Patent No. 165,278 also (paragraph 1) the calcium perborate is stated to bevery unstable as compared with other perborates. Ihave found in fact that such unfavorable results are obtained when calcium chlorid'is caused to act on sodium 1 perborate in the usual way in the manner set out in these references. When for example a concentrated solution of sodium perborate is convertedwith the equivalent quantity of calcium chlorid,'the precipitated calcium perborate contains about oftheactive oxygen employed. The calcium perborate thus obtained'was found, after drying, to haveanaverage oxygen content of 8.5%. 30 percent. of the active oxygen employed had remained behind in the mother liquor,

' theremainder, 26 per cent, had disappeared little water, the solution warmed, and solid crystallized sodium perborate added to the concentrated solution, the known reaction at once occurs. A precipitate of calcium perborate is at once formed and sodium chlorid is produced. The calcium perborate is formed in clots or lumps and may with advantage be ground up again with the whole reaction massin order that inclosed particles may be Specification of Letters Patent; Patent d. A110, application filed March 14, 1a11.- Serial No. 614,443. r

subjected to the reaction. The perborate may also be added mixed with Water.

\Vhen the quantity of water used is sufficient for" permitting the sodium chlorid formed to go into solution, the calcium perborate is drained by suction and so thereby freed from the sodium chlorid solution. It is possible, however, to work with less water, and even to limit this to the water of crystallization. In this case, after completion of the reaction and cooling, sufiicient water has to be added toibring all the sodium chlorid into solution; the precipitate is then drained by suction'and wit-shed with water. With this method of working, the conversion may with advantage be carried out in ball mills.

When the calcium perborate is actually formed, it ismuch less sensitive to water and it can therefore be mixed with an ample quantity of water for dissolving out the sodium chlorid. It appears therefore that it is only during the actual formation of the calcium perborate that the water exerts an essentially hydrolytic action.

It is not necessary to start with ready formed alkali perborate. I can also employ substances which. yield alkali perborates', e. 7.

hydrogen peroxid plus a kali borate, or alkali superoxid plus boric acid plus mineral acid. In general, all those substances may .be considered from which perborates may be produced in the well known manner. As sodium perborate itself is rather insoluble it is of advantage to carry out the reaction at a raised temperature.

The result attained by the present invention was notto be foreseen from the literature on the subiect. since according thereto only an unstab e calcium. perborate is obtained which could not even be analyzed. Further, from the publication to a similar effect in the Oomptes Rcmlus 140,508. where it is likewise stated that sodium perborate is converted by calciuinsalt into a calcium perborate varying in composition according The reaction need not nece sarily be car- Ild out With equivalent qnaaltities, but the salt can be employed in excess, in this case it goes into the mother liquor on filtration Example: 11 parts; 1%.: molecule) of crystallized calcium clori'd-Earedissolved in partsaof Water and heated to 50 60 C. To

weight. In this example 9.5 per cent. of the active thisjisolution are added 15.4 parts (1 molecule) of commercial sodium perborate. Calcium perborate separates out in clots or lumps. The temperature is kept at- 60 C. and the mass is ground up until a homogeneous paste is formed. The mass is then allowed 'to cool and 5 parts of cold Water are added. After standing for a" While the calcium perborate is drained by suction and Washed with a small quantity of Water. On

, drying in the air, a product is obtained which contains about 12.3% of active oxygen; The quantity amounts to about ll pa-rts by The oxygen yield is about 90%.

oxygen'was still found to be present in the mother liquor, so that in this case only 0.5% was lost in the process. The mother liquor canf-be used again as a solvent on another batch of material. VVhen the process is car- .riedfout with more Water, the yield of calfc'ium perborate is smaller, While when less Water is taken the yield is higher. The calciumfperborate thus obtained'is distinguished by ahigh ox: gen content and is extremely suitable ,for beaching purposes, as it Withstandsboilisng with water much better than sodiu.m==perborate.

The essence of the present-processconsists I in the'factthat thehydrolytic action of the Water during the formation of the calcium perb'orate is restrai v ed or in other WOI'dS,

that water in quantity insuflicient to cause any material amount of hydrolytic action on the ca'lcium perborate is employed during the reaction. This can be attained not only in the Way described by reducing the.qu,an tity of Water, but also by diluents', which have the property of reducing or restraining the hydrolytic action of the Water during the reaction.

I claim:

1. The process herein described of pro? ducing stable perborates, Which consists in subjecting an alkali perborate to the action ot a calcium salt in the presence of Water insuflicient in quantity to cause any material amount of hydrolytic action during the re action.

2. The process herein described of producing stable calcium perborates which consists in subjecting sodium perborates to the action of calcium chlorid in the presence of Water insufiicient in quantity to cause any material amount of hydrolytic action during the formation of the'ca-lcium perborate.

3. The process herein described of producing stable pcrborates, Which consists in subjecting an alkali-perborate to the action of a 'insuflicient in quantity to cause .any material amount of hydrolyticlaction, reducingthe clots or lumps of the calcium perborate formed by the reaction by grinding, separating the calcium perborate from the mother- 'liquor, and lastly, Washing the same with Water. In testimony, that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

REINHOLD GRllTER.

lVitnesses:

PAUL SoHUmzn, MAX MAETSCHKE. 

